PK232.21

From: W5IFP@W5IFP

AS A RESULT OF THE BULLETIN I SENT ON USING 2 TNC'S ON ONE RTU,
SEVERAL HAVE REQUESTED THE SPECIFIC DATA ON THE PK-232 TNC.
THERE ARE SEVERAL WAYS TO MODIFY THE PK-232 TO ACCOMPLISH THE DATA
INVERSION ON THE SQUELCH OR REC. DATA LINE (RF-DCD). I HAVE A  HEATHKIT
HK-232 SO I'LL USE THAT FOR EXPLANATION...HOPEFULLY THE CKT DESIGNATIONS
ARE THE SAME AS THE AEA PK-232. THE FOLLOWING IS A CROSS REF TO PIN #'S:

DATA           MFJ-1270             RTU              HK-232
----           ------              ------            ------
GND            PIN 2 ------------- PIN 2 ------------ PIN 4
TX AUDIO       PIN 1 ------------- PIN 1 ------------ PIN 2
RX AUDIO       PIN 4 ------------- PIN 4 ------------ PIN 1
PTT            PIN 3 ------------- PIN 3 ------------ PIN 5
RF-DCD (SQU)   PIN 5 ---->------- PIN 3 -------                        1N914                   1N914

* THE SQUELCH LINE MUST HAVE THE LOGIC SIGNAL INVERTED TO WORK . THIS CAN
BE DONE INTERNALLY BY CHANGING Q6 FROM A NPN TO A PNP TRANSISTOR. GARDEN
VARIETY WORKED OK (2N3906 OR 2N2905 OR EQ.)
CONTINUED IN FILE PK232.22